Box stacker



C. STRAW ox STACKER 6 Sheet s-Sheet 1 Filed Feb. 10, 943

c. STRAW v BOX STACKER 6 Sheets-Sheet 2 Filed Feb. 10 194:;

Oct. 19,1948. STRAW 2,452,020

. BOX STACKER Filed Feb. 10, 1943 6 Sheets-Sheet 3 c. sTRAw BOX STACKEROct. '19, 1948.

Filed Feb. 10, 1943' IIIIIIIIII IIHIIIIII/r C- STRAW BOX STACKE B Oct.19, 1948.

6 Sheets-Sheet 5 Filed Feb. 10, 1943 Oct. 19, 1948. c. STRAW 2,452,020

BOX STAGKER Filed Feb. 10, 1943 6 Shets-Sheet 6 62A yroxy srfm w a(Mm-MM,

Patented Oct. 19, 1948 UNITED STATES PATENT OFFICE,

' Box STACKER Clayton Straw, Henniker, N. H., assignor to Kingsbury &Davis Machine (Jompany, Contoocook, N. H, a corporation of New HampshireApplication February 10, 1943, Serial No. 475,453

4 Claims. 1

This invention relates to the manufacture of paper boxes, and tostacking devices primarily for use as adjuncts to paper-box-makingmachines for the purpose of assembling the boxes successively dischargedfrom the box-making machine into coherent nested relation so as to formcompact stacks facilitating handling, shipment, and storage, and todispose the boxes in safe and orderly manner as discharged from thebox-making machine.

The main object of the present invention is to provide stacking deviceswhich will receive opentop parallel-sided boxes, including under thisterm the similarly shaped covers therefor, singly as discharged from abox-making machine, and interengage two corners and a, substantialportion of the bottom and side walls of each box adjacent thereto withinthe corresponding portions of the next preceding or succeeding box, soas to wedge the two together in coherent relation. As is well known,since the interior dimensions of the boxes involved are the same at bothtop and bottom of the boxes, it is not possible to telescope the boxesinto a nested relation in which the bottoms are parallel, because thebottom of one box will not pass Wholly within the open top of a similarbox of identical size. Hence it is customary to assemble them in themanner just indicated, with two corners of one box inside and twocorners thereof outside the adjacent box and in overlapping or ofisetrelation, with their hottoms in alternateIy oppositely-tilted and thusin zigzag relation.

The present invention attains this stacking or nesting of the boxes innovel and improved manner through feeding the successive boxes inalternately oppositely-tilted relation to each other, either open-sideor bottom-side first, and each in offset, overlapping,vertically-displaced relation to its predecessor, so that before makingcontact with each other the successive boxes are both alternately tiltedto bring their bottoms into the zigzag relation they must assume to eachother and also are in the staggered relation which admits two corners ofone box within the corresponding corners of the adjacent box. At thesame time, yielding resistance is opposed to the travel of the boxes asthus fed, so as to cause each box as fed to be wedged into coherentrelation with its predecessor and to push the stack onward sufficientlyto make room for the next box to be added thereto.

This is accomplished in the present embodiment by receiving the boxdischarged from the box-making machine upon a table or against a stopwhich supports or stops it through engagement with the side or end ofthe box, which table or stop changes its position to arrest alternateboxes after a lesser degree of travel, and intermediate boxes after agreater degree of travel, from the box-making machine, while a plungerwhich engages the bottom of the boxes shoves the boxes successively offfrom the table or away from the stop in a direction substantially atright angles to their previous direction of movement. The working faceof the plunger changes its slant after successive working strokes sothat one side or end of a given box is slightly in advance of the restof such box as it is pushed forward by the plunger while the oppositeside or end of the next succeeding box is in advance when thus fedforward by the plunger, so that the successive boxes before they reachthe stack are thus given the overlapping and zigzag relationship whichcomprises their ultimate position when nested together in the stack.

Additional features of the present invention comprise novel means in theform of brushes yieldingly engaging the sides of the stack of boxes tohold it back suiiiciently to insure proper nesting of the successiveboxes as each is added thereto while permitting onward travel of thestack under push of the added box without opposing sufficient resistanceto cause crushing of the boxes. A further feature comprises the use of adetent or escapement in the form of a star wheel to hold back thesuccessive boxes and release them in proper timed relation to be handledcorrectly by the stacking members, regardless of their rate of feed fromthe box-making machine to the stacker. Another feature is the provisionfor driving the box stacker from the box-making machine by means ofdriving connections admitting of easy attachment and disconnection ofthe two machines. A further feature is the provision for folding therack holding the stacked boxes back over the machine when not in use.

Other aims of the invention, and the manner of their attainment, are asmade plain hereinafter.

An illustrative embodiment of the invention is shown in the accompanyingdrawings, in which:

Fig. 1 is a side elevation of the main parts of the box stacker, showingits driving and feeding connections with the box-making machine.

Fig. 2 is an elevation similar to Fig. 1, showing the other side of themachine.

Fig. 3 is a view in vertical section on line 3-3 of Fig. 5.

Fig. 4 is a view in vertical section on line 4-4 of Fig. 5.

Fig. 5 is a view in horizontal section on line 5-5 of Fig. 2.

Fig. 6 is a view from above, looking down on the machine obliquely inthe direction of the arrow shown at 6 in Fig. 2.

Fig. 7 is "a view in-section on .the line 'i-l of Fig. 2.

Fig. 8 is a section on line 88 of Fig. 2.

Fig. 9 is a sectional elevation on line 3 of Fig. 2.

Figs. 10 and 11 are sectional views on the lines l0l6 and 11-4 I, ofFig. 8, respectively.

Fig. 12 is a view in section on line I2l2 of Fig. 2.

Fig. 13 is a detail of the ratchet actuating the star-wheel detent whichtimes the feed of the boxes.

Fig. is is a section on line lei-4t of Fig. 2.

Fig. 15 is a section on line l5it of Fig. 6.

The box stacker of the present invention is intended to be used toreceive and stack entirely automatically the output of boxes from boxmaking machines of conventional type such as the well-known Kingsbury &Davis quadruple box-staying machine, shown in U. S. Letters Patent No.728,086, granted May 12, 1903.

The box stacker is preferably but not necessarily driven by power takenfrom the box-making machine. For this purpose, a novel power take-off isprovided, as shown in Fig. l, which facilitates connecting up anddisconnecting the box stacker from the box machine, and at the same timetransmits the necessary driving power to the box stacker withoutexerting any material pull or push such as is involved in a belt drive,thereby enabling the box stacker to be mounted on wheels for easyportability and avoiding the necessity for bolting the machinepermanently to the floor to hold the box stacker in operative relation.Hence'a single box stacker can serve a number of box making machines insuccession. Thus, main driveshaft 49 of the box stacker is driven fromthe cam shaft 8 of the box machine by a chain 9 and sprockets Ill, H,the latter sprocket being loose on a shaft l2 mounted in a housing l3bolted at M to the frame I of the box-making machine, a shear pin l5transmitting the drive from sprocket II to an arm i6 keyed and clampedto shaft 12. Bevel gears il' drive a socket l3 outside the housing, inwhich socket is received the ball-shaped extremity IQ of a shortpropeller shaft 26, a transverse pin 2! extending out from each side ofthe ball and being received in a slot 22 in socket E8 to form auniversal joint connection. A similar connection between the other endof shaft 26 and a corresponding socket 23 on a housing 24 on the outsideof frame 29 of the box stacker transmits the drive to a pair of bevelgears 25, one of which is fixed on the end of mainshaft 49 of the boxstacker. To set up the drive, it is merely necessary to roll the boxstacker on its wheels 25 into a position Where its apron 3 is in roughalign ment with delivery apron 2 of the box-making machine, and guidethe two ends of driveshaft 20 into the two sockets i8, 23, as themachines are brought together. A pair of clamps 21 bolted to the floorhave raised slotted extremities into which the rims of the leading pairof Wheels 26 are introduced, screws 28 thereupon being tightened againstthe webs of wheels 26 within their rims to hold this machine in drivingconnection with the other.

The box-making machine, indicated fragmentarily at I, has the endlessapron conveyor 2 which receives the boxes as completed and dischargesthem out of the machine. A similar apron conveyor 3 is provided in thestacking machine, and arranged with its outer end at the same level andin close proximity to the delivery end of the conveyor on the box-makingmachine, so that the successive boxes carried by the first conveyor willride off of the end thereof and onto the conveyor of the stacker withoutpause. This conveyor 3. is borne by rolls 4, freely rotating in bracketsextending out from frame 23, one of such rolls being an idler adjustablein its position to tighten the belt, and by a roll 5 rotatable on pivots6 fixed in frame 29 and driven by a belt I and V-pulleys 6 frommain-drive shaft 49 of the stacker.

The boxes 3!! fed from the box-making machine l by conveyor 2 ontoconveyor 3 of the stacker are discharged one after another into aninclined hopper defined by downwardly-extending sheet metal wings 32,guards 34 being provided in hinged connection with these wings tooverlie each margin of conveyor 3 to confine the boxes against lateralescape. Each box in turn descends over the inclined surface of aflatfaced pusher 36, Figs. 4, 7, and 12, working in,

an inclined wall 31 of the hopper and which performs the operation ofpushing the boxes together into nested or stacked relation. As theyslide down over the face of pusher 36, alternate boxes come to rest withtheir lower ends against the bottom 38 of the hopper, while theintermediate boxes are arrested at a higher level by engagement with thetwo raised ribs 40 of a stop 42 rising and falling in an aperture formedfor it in the bottom 38 of the hopper. The bottom end of pusher 36 isslotted at 44, the raised ribs Ml entering these slots when the stop iselevated, so that each member can perform its desired motion even whenthe working faces of the two members are in overlapping and intersectingrelation as shown in Fig. 4.

To cause stop 42 to assume alternately an elevated and depressedposition, so as to arrest the alternate boxes sliding down over thepusher 36 at a higher level than the intermediate boxes of the series,stop 42 has an integral shank 46, Fig. 7, which is formed as indicatedat 48 in Fig. 4 to straddle a shaft 14 mounted in bearings 16 in themachine frame and driven at half the speed of main shaft 49 by gearing18, 8!), 82. Stop 42 is equipped at each side with a projecting pin 50sliding in guideways 52, Fig. 7, in a frame-member 55 supporting thehopper bottom 38. A cam follower '56 on the shank 46 works in a path 58in a closed cam 66 fixed on shaft 14, thus alternately lifting stop 42and depressing it until its ribs 49 are flush with the bottom 38 of thehopper. This change in the elevation of the ribs 43 imparts theessential vertically oiiset relation to the successive boxes to presentone end-portion of the preceding box intermediate the length of theslightly flaring sides of the oncoming box, thus enabling them to nesteasily.

The pusher 36 makes its stroke across the bottom 38 of the hopper topush a box dropped in front of it onto the end of the stack, by reasonof its being carried by a bracket 62, Figs. 4 and 5, which is pivotallyconnected at 64 with a lever 66 mounted on a stud 68 in the machineframe, such lever being actuated by a cam follower on a pin 10 in thelever and working in a path cam I2 fixed on main shaft 49.

While lever 66 imparts a forward and backward movement to pusher 36, theworking face of the pusher is alternately tilted during its workingstroke 50 that its upward end travels faster than its downward endduring one working stroke, and then during its next working stroke itsdownward end travels faster than its upward end, and so. on inalternation, by a pin 84 fixed in an extension 86 on bracket 62 andcarrying a roll working in a slot 88 in a path cam 96 attached to theface of a plate 92 having a shank 94, Fig. 5, swiveling in a bracket 96on the inside of the machine frame 29. Path cam 96 is pivotallyconnected at 98 with a link I66 pivoted at N12 to one end of a lever I64mounted on a stud 69 on the frame and having a roll I08 pivoted on itsopposite end engaging a cam H0 fixed on shaft 14. Thus, with the partsin the relation shown in Figs. 3 and 4, upon rotation of shaft 49 forone-half turn pin 84 follows a path higher than that of pin 64 whichsupports the pusher and its bracket on lever 66, with the result thatthe top of pusher 36 travels forward faster than the rest of the pusherssurface, thus pushing the box which has been dropped in front of itforward toward the stack with its upper end in the lead while the wholebox is held in elevated relation above the bottom 38 of the hopper bythe rails 46 on account of the elevated position of stop 42. Continuedrotation of shaft 49 for another half turn causes cam 12 to retractpusher 36 back to its position illustrated in Fig. 4, its startingpoint, while the accompanying quarter-turn rotation of shaft l4 and cam60 lowers stop 42 until its rails 46 are level with the bottom 38 of thehopper. Atthe same time, this latter rotation of shaft 49 causes cam H6to move lever I04 so as to depress the free end of cam 96, so that afterthe next box is dropped by conveyor 6 in front of pusher 36 the latterwill travel forward with its bottom end in the lead, upon continuedrotation of cam 'i2 in counter clockwise direction, and will thrust thebox across bottom 38 of the hopper with the boxs lower end in advance ofthe rest of the box and depressed below the bottom of the immediatelypreceding box. In this way both the staggering of the boxes whichenables two corners of one to enter within the interior of its adjacentbox, and the oppositely-tilted oblique or zigzag relation of the planesof the bottoms of successive boxes which enables them to nest compactly,are attained.

To increase the relative obliquity given to the successive boxes aspushed forward by pusher 36, for proper nesting of deeper boxes thanthose shown,-the position of the pin 98 is shifted along the small slotI 13 in cam 86 in which it is shown mounted, in a direction toward thecams pivot 94, to increase the throw of the cam, the pin beingthereafter operatively fixed.

To keep the alternate boxes, when advanced with their bottom edges inthe lead by the backwardly tilted pusher 36, from lifting the stack upoff of the floor of the stack-supporting surface I I2 on which it rests,the amount of the changed inclination of pusher 36 during successiveworking strokes is not divided equally each side of the line of thrustof the pusher 36 toward the stack, but is mostly added to the slant ofthe pusher when the latter advances with its top edge in the lead andhence pushing the intermediate boxes on to the stack with their topedges in advance of their bottom edges. This is accomplished bythreading link it!!! into its clevises at each of its ends with screwthreads of opposite hands, so

that its effective length can be adjusted to tip cam 9t up or down asneeded to vary the relative elevation of the free end thereof, withoutaffecting the scope of movement imparted to this cam by link Hill as setby the position of pivot 98.

Pusher 36 returns after each stroke into the same position in the planeof the inclined wall 3? of the hopper because pin 84 passes along groove88 in cam 90 until coaxial with the pivot 94 of such cam as shown inFigs. 3 and 4. Thus the momentary position or continuing movement of cam96 has no effect on the slant of pusher 36 at this time, and the latteris retracted flush with wall 3'! to permit each box to descend thereoverwithout catching on the top edge of the pusher.

Obviously, the boxes can be fed onto the stack either with their opensides or with their bottom sides forward. The present device is arrangedto shove the boxes onward into nested relation with their open sidesforward, as this avoids the problem of getting the pusher 36 to enterwithin the box interior without catching on the upstand be extensiveenough to make sure that the bottom of the box will take the same slantas that of the working face of the pusher. For the purpose of causingthe bottom of the box thus to conform to the slant of the pusher, thewhole hopper is tilted backwardly toward the boxmaking machine, so thatgravity will cause the box bottom to rest accurately and conformablyagainst the working face of the pusher. However, if preferred, thehopper wall 37! and pusher can be disposed either vertically, with thestacksupport I I2 which receives the accumulated stack of nested boxesarranged horizontally, or the hopper wall 3'! and pusher can behorizontal with a vertical stack-support on two or more sides of thestack.

Each box as thrust forward by pusher 36 is forced between two pairs ofbristle-clad members or brushes H4, Figs. 6, 12 and 14., in holders H6which are set at the proper spacing widthwise of the machine toengage'the vertical sides of each box as it is pushed forward by pusher36 and to oppose a moderate amount of resistance to the forward movementof the boxes under presssure of the pusher. This pressure combined withthe movement of the boxes bends the bristles in the direction of thefeed causing them to resist reverse movement of the boxes. When stop 42is in its depressed position the top surfaces of its ribs 46 aresubstantially in line with the bottom 38 of the hopper which latter isin the plane of the stack-supporting surface H2 which forms the floor ofan extending rack i l6 made lon enough to hold an accumulation of arelatively large number of boxes in staggered relation, and from whichthe stacked boxes are removed by hand periodically for use or forstorage in nested form. Thus every other box, being pushed uphill alongbottom 38 to the limit of the stroke of pusher 36, passes between and isheld by brushes H4, its side-walls passing over the protrudingend-"portion of'its predecessor, and under pressure of the succeedingboxes is slid upward along stack-support 2. The intermediate boxes areelevated from bottom 38 through the alternating elevation of stop 42which assists in attaining the nested relation, and each is likewisethrust between the brushes and over the end-portion of the lowermost boxin the stack The brushes I I4, aided by the resistance to uphillmovement opposed by the stack as it accumulates, affords the necessaryresistance to insure each successive box being fully nested over itspredecessor. Clamp screws I20 put through slots I 22 in uprights I24enable the brushes to be adjusted to the proper heights for differentlengths of boxes. The angular foot portions I26 on uprights I2 aremounted for adjustment widthwise of the machine, each foot having ashouldered portion slidably fitting between two parallel guide-edges I28extending transversely across the machine between the terminus of bottom38 of the hopper and a plate I30 forming an extension of the floor II2of the stack'support. Manually operable clamp screws I32 are fixed inscrew threaded sleeves I 34, Figs. 2 and 12, which have shouldersengaging the under sides of guide-edges I28 along the parallel edges ofthe latter. These sleeves ar oppositely threaded and receive a threadedshaft I38 revolved by hand-crank I 38 and itself held from endwisemovement by a central shoulder I40 held rotatably in a block I42 screwedto frame member I44 at midwidth of the machine. When handnuts I40 areloosened, rotation of adjusting screw I36 by its crank moves theuprights and the brushes inward or outward tosuit boxes of differentwidths. Tightening the hand-nuts I06 clamps the feet I25 and the sleevesI34 against the guide-edges to maintain the adjustment. The wings 32 ofthe hopper are likewise supported on brackets extending from theuprights I24, so that this adjustment also sets the width of the hopperand the spacing of side guards 34 carried thereby, correctly for thewidth. of box being turned out. The wings 32 steer the oncoming boxaccurately over the last preceding one held by the brushes.

To feed the boxes into the hopper in properly timed relation to themovements of pusher 36, a revolving detent or escapement device in theform of a star-wheel MB is employed, having hooked radial arms whichextend downward into proximity to the surface of conveyor 3 to enterwithin the open top of each box as it is carried past by the conveyorand to hold back the box, releasing it at the proper moment to cause theconveyor to discharge it into the hopper over pusher 36 while the latteris in the fully retracted position shown in Fig. 4.

To do this, detent I48 is fixed on a shaft I50 so as to stand atmidwidth of conveyor 3, the shaft being rotatably mounted in a bearingI52 at the free end of a supporting arm I54 pivotally mounted on a studI55 fixed in th upper end of an arm I58 whose lower end is clamped infixed angular position about the protrudin end of one pivot 6 on whichroll supporting the conveyor rotates (Figs. 2, 6 and 12). An arm I60,clamped in fixed angular position to stud I56, has an angularly bentextremity which supports arm I54 and thus the star-wheel at the desiredelevation above conveyor 3, in a manner allowing the star-wheel to risefreely without disarranging the setting or damage to the parts in theevent that two boxes arrive beneath the star-wheel one on top of theother, as sometimes occurs. The end of pivot 6 rotatably supports asprocket which when totated transmits rotation to star-wheel M8 by meansof chains I62, I94, a pair of connected sprockets on stud I56, and asprocket fixed on shaft I50 carrying star-wheel I48. Fast with thesprocket on pivot 5 is a ratchet I66, Fig, 13, actuated by a pawl I60 onan oscillating pawl-carrier I70 which is actuated by a link "2 having aforked lower end which straddles the end of shaft 49 which projectsoutwardly through side frame 29. A cam I74 fixed on the end of shaft 49engages a roll I'lfi on link I12 to move the link and hence thepawl-carrier II! with its pawl in one direction to give the pawl itsidle stroke, while contracting springs I18 move the link in the oppositedirection to give the pawl its working stroke rotating star-wheel I48 tolift its acting arm out of the box bein detained thereby, andimmediately thereafter to put its succeeding arm down inside thefollowing box to hold that one back until the pusher 36 has disposed ofthe preceding box and is ready to receive the next one. Since there is adwell of the star-wheel after it arrests each box and while the pusheris stacking the preceding box, friction means is provided to preventvibration of the machine coupled with the drag of continuously movingconveyor 3 against the bottom of the detained box from shifting thestar-wheel sufliciently to release the box prematurely. This comprises abrake shoe I80, Fig. 15, having its reduced shank portion held in aguide-sleeve I82 fixed on the side of the bearing I52, the block beingpressed yieldingly against a collar I84 fixed on shaft I50 by a. screwI86 and interposed spring I88 so as to create friction enough to holdthe star-wheel against accidental rotation.

This arrangement of the star-wheel detent permits it to be moved forwardor back along conveyor 3 to suit boxes of varying length, or lowered orraised for boxes of different depth, without losing the pro-per timingof its release of the successive boxes; thus there is no occasion tochange the setting of cam I14.

The extended rack II8 which holds the stack of nested boxes accumulatingin the machine is arranged so that it can be folded back over the bodyof the machine to get it out of the way when the stacker is not in use.For this purpose, the rack swings around a transverse axis at I90, Fig.2, a short distance beyond the guide-edges I20 and at the terminal edgeof extension-plate I30. To create this axis in the plane ofstack-supporting surface I I2 and of plate I30, segmental guides I92,Figs. 2, 8, 9, and 10, are bolted to the inner surfaces of side frames29 of the machine, by means of screws I90 passing through suitablebosses in the webs of the frames and threaded into lugs i96 on theguides. Corresponding guide-members I 98, Figs. 8, 9, and 11, havingsemi-circular tongues 200 fitting within the semicircular grooves 202 ofguides I92, are bolted at 205 to a cross-member 206 to the ends of whichare fixed by'screws 208 the flanged ends of anglesection members 2H?supporting the stack-supporting surface I I2 forming the floor ofextended rack II 8.

To hold the stack of nested boxes on the surface II 2 of the extendedrack, side guards 2I2, Fig. 2, are provided, each pivotally supported at2 well above the surface H2 by a member 2I6 rigidly secured at its lowerend to an elongated strip 2H3 affixed to the inward surface of eachupright I24 carrying the brushes II 4, and having its lower end outsideof and fixed to the foot of each wing 32 defining the hopper. Thusmounted, the same adjustment which sets the uprights, brushes, and wingsto suit the width of the boxes being stacked, also adjusts the sideguards 2I2 toward and from each other to suit the width of the boxes,while the pivotal connection at 2 I4 lets the guards fold back over themachine along with the extended rack H8. A suitable support (not shown)rigidly attached to the upper end of each side guard 212 and extendingat right angles to rest upon the surface H2 of the rack, maintains theupper ends of guards 2l2 in elevated position roughly parallel to thesurface H2, when the machine is in use.

While I have illustrated and described a certain form in which theinvention may be embodied, I am aware that many modifications may bemade therein by any person skilled in the art, without departing fromthe scope of the invention as expressed in the claims, Therefore, I donot wish to be limited to the particular forms shown, or to the detailsof construction thereof, but what I do claim is:

1. Stacking devices for boxes having in combination means feeding theboxes one by one, a surface supportin the boxes, a pusher engaging theboxes one by one and pushing them in the same direction over suchsupporting surface, and means varying the angular inclination of thepushing surface of the pusher by causing one end of the pusher to be inthe lead during alternate working strokes and the other end to be in thelead during the intermediate working strokes.

2. Stacking devices for boxes having in combination means feeding theboxes one by one, a surface supporting the boxes, a pusher engaging theboxes one by one and pushing them all in the same direction over suchsupporting surface, and means causing the pushing surface of the pusherto assume alternately oppositely-tilted relation when it completes thepushing of successive boxes.

3. Stacking devices for boxes, having in combination means feeding theboxes one by one, a surface supporting the boxes, a pusher engaging theboxes one by one and pushing them all in the same direction along suchsupporting surface, means varying the angular inclination of the pushingsurface of the pusher during its successive working strokes so as toadvance the boxes to the stack of accumulated boxes in alternatelyoppositely-tilted relation, and means varying the path of travel of eachsuccessive box while engaged by the pusher.

4. Stacking devices for boxes having in combination means feeding theboxes one by one, a surface supporting the boxes, 2. pusher engaging theboxes one by one and pushing them all in the same direction over suchsupporting surface,

means reversing the angular inclination of the pushing surface of thepusher on successive working strokes, after pushing each successive box,and means varying the amount of angular inclination to suit boxes ofdifferent depths.

CLAYTON STRAW.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,010,828 Vaughan Dec. 5, 19111,289,208 Lents Dec. 31, 1918 1,364,562 Laughton Jan. 4, 1921 1,431,895Purcell Oct. 10, 1922 1,433,328 Wright Oct. 24, 1922 1,564,477 GlassDec. 8, 1925 1,721,900 Doiron et a1. July 23, 1929 1,896,177 KnowltonFeb. 7, 1933 1,961,366 Knowlton l June 5, 1934 2,198,949 Redman Apr. 30,1940 2,306,431 Exley Dec. 29, 1942 2,323,359 Sillars July 6, 19432,345,012 Sillars Mar. 28, 1944 2,345,645 Wickwire et al Apr. 4, 1944FOREIGN PATENTS Number Country Date 756,334 France Sept. 18, 1933

